WO2006106459A1 - Procede pour utiliser un noeud d'un reseau de communication, noeud de reseau, reseau de communication, support lisible par ordinateur et element de programme - Google Patents

Procede pour utiliser un noeud d'un reseau de communication, noeud de reseau, reseau de communication, support lisible par ordinateur et element de programme Download PDF

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Publication number
WO2006106459A1
WO2006106459A1 PCT/IB2006/050980 IB2006050980W WO2006106459A1 WO 2006106459 A1 WO2006106459 A1 WO 2006106459A1 IB 2006050980 W IB2006050980 W IB 2006050980W WO 2006106459 A1 WO2006106459 A1 WO 2006106459A1
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Prior art keywords
communication channels
communication
counting down
network
network node
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PCT/IB2006/050980
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English (en)
Inventor
Georgios Orfanos
Joerg Habetha
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Koninklijke Philips Electronics N.V.
Philips Intellectual Property & Standards Gmbh
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Publication of WO2006106459A1 publication Critical patent/WO2006106459A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0833—Random access procedures, e.g. with 4-step access
    • H04W74/0841—Random access procedures, e.g. with 4-step access with collision treatment
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W74/00—Wireless channel access
    • H04W74/08—Non-scheduled access, e.g. ALOHA
    • H04W74/0866—Non-scheduled access, e.g. ALOHA using a dedicated channel for access
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/10—Small scale networks; Flat hierarchical networks
    • H04W84/12—WLAN [Wireless Local Area Networks]

Definitions

  • the invention relates to the field of networks.
  • the invention relates to a method of operating a network node of a communication network, to a network node, to a communication network, to a computer-readable medium, and to a program element.
  • a WLAN Wireless Local Area Network
  • a WLAN may be implemented in the frame of the standard IEEE 802.11 (see LAN MAN Standards Committee of the IEEE Computer Society, Wireless LAN Medium Access Control (MAN) and Physical Layer (PHY) specifications, IEEE Standard 802.11, 1999 Edition).
  • IEEE 802.11 is a worldwide standard for Wireless Local Area Networks
  • WLANs constantly improving in order to cope with the raising demands of users and applications for higher throughput and Quality of Service (QoS).
  • QoS Quality of Service
  • CSMA Carrier Sense Multiple Access
  • WLAN Wireless Local Area Network
  • IEEE 802.11, respectively CSMA/CA is based on a listen before talk scheme. Stations listen to the medium and start a packet transmission of arbitrary length (up to a certain maximum) after detecting that there is no other transmission in progress on the wireless medium. However, if two stations detect a channel as "idle" (i.e. not busy) at the same time and both send a communication message, a collision occurs.
  • the standard IEEE 802.11 defines a Collision Avoidance (CA) mechanism to reduce the probability of such collisions.
  • CA Collision Avoidance
  • a station before starting a transmission, a station performs a backoff procedure.
  • the backoff procedure foresees that a station has to keep sensing the channel for an additional random time after detecting the channel as being idle for a minimum duration called Distributed Coordination Function Interframe Space
  • Fig. 6 shows a scheme 600 illustrating a prior art CMSA/CA access according to IEEE 802.11.
  • the scheme 600 shows a first station 601, a second station 602, a third station
  • Fig. 6 shows Distributed Coordination Function Interframe Spaces (DIFS) 607, Backoff Downcount periods 608, Rest Backoff periods 609, and Frame periods 610.
  • DIFS Distributed Coordination Function Interframe Spaces
  • the Mobile Station which has a data packet 610 to transmit, draws a random number between 0 and CW (Contention Window), which determines the duration of the Backoff timer in number of slot times.
  • the Contention Window has a minimum starting value of 15 and it doubles after a packet collision. Its value can rise up to 255 and is decremented after a successful transfer. The doubling of the CW size reduces the probability that the same packets collide again.
  • the receiver acknowledges a successful transmission with an Acknowledgement (ACK) frame. A collision is detected by a missing ACK frame.
  • ACK Acknowledgement
  • the station While the medium is free, the station counts down the Backoff timer until it reaches zero and, after having scanned the medium as free for at least a DIFS time, starts the transmission. If during the countdown another station occupies the medium, all stations in backoff interrupt their countdown and defer until they detect that the medium is free again for a time of at least the duration of the DIFS. Then they continue the countdown at the Backoff timer starting at the previously frozen value. This ensures that stations, which deferred from channel access because their random Backoff time was larger than the Backoff time of other stations, are given a higher priority when they resume the transmission attempt. After the successful transmission of a packet, a station starts a new Backoff procedure even if no other packet is waiting in its queue for transmission. The latter is called post-Backoff.
  • a system can comprise multiple channels which are operating independently of one another.
  • channels are defined by different center frequencies.
  • CDMA Code Division Multiple Access
  • each data symbol is spread over a large bandwidth, larger than the bandwidth needed for transmission. This allows to transmit with a spectral energy that is lower than a non-spread spectrum system, a fact that allows the use of parallel transmission channels at the same time in the same frequency band.
  • the data transmitted in the different channels can be distinguished by the use of a different spreading code for each channel.
  • the data stream comprises a successive sequence of symbols or chips.
  • DS-CDMA Direct- Sequence CDMA
  • MC-CDMA Multi-Carrier CDMA
  • MC-CDMA is suitable for WLAN, because existing WLAN versions are so- called multi-carrier systems.
  • a multi-carrier technique like Orthogonal Frequency Division Multiplexing (OFDM) allows for the parallel transmission of data on several subcarriers. Due to the Fast Fourier Transform (FFT) associated with Orthogonal Frequency Division Multiplexing (OFDM), MC-CDMA chips are long in time duration, but narrow in bandwidth.
  • FFT Fast Fourier Transform
  • MC-CDMA chips are long in time duration, but narrow in bandwidth.
  • Each symbol of the data stream of one user is multiplied by each element of the same spreading code and is thus placed in several narrow band subcarriers. Multiple chips are not sequential, but transmitted in parallel on different sub-carriers.
  • US 2005/0044249 Al discloses a method and an apparatus for unifying medium access control (MAC) protocols that can unify various existed MAC protocols, e.g. slotted ALOHA protocol, carrier sense multiple access (CSMA) protocol, group randomly addressed polling (GRAP) protocol.
  • the method comprises grouping the MAC nodes having a ready packet according to preset parameters, and transmitting packets according to the grouping result and the preset parameters.
  • US 2005/0044249 Al discloses that MAC nodes in different groups can send their packets via different channels so as to avoid or resolve collisions. However, such conventional collision avoidance systems may suffer from limited efficiency concerning usage of channel capacity.
  • a method of operating a network node of a communication network comprising a plurality of network nodes communicating via a plurality of communication channels, the method comprising counting down a pre-determined waiting time before transmitting a signal via a selected one of the communication channels, detecting, during the counting down, whether the selected one of the communication channels becomes busy, and, in case that the selected one of the communication channels becomes busy during the counting down, switching to another one of the communication channels and continuing the counting down on the other one of the communication channels.
  • a network node for a communication network comprising a plurality of network nodes communicatively coupled via a plurality of communication channels
  • the network node comprising a processor adapted to control or carry out the above-mentioned method.
  • a communication network comprising a plurality of interconnected network nodes having the above-mentioned features.
  • a computer- readable medium in which a computer program of operating a network node of a communication network comprising a plurality of network nodes communicating via a plurality of communication channels is stored, which computer program, when being executed by a processor, is adapted to control or carry out the above-mentioned method.
  • a program element of operating a network node of a communication network comprising a plurality of network nodes communicating via a plurality of communication channels
  • which computer program when being executed by a processor, is adapted to control or carry out the above-mentioned method.
  • the communication schema according to embodiments of the invention can be realized by a computer program, i.e. by software, or by using one or more special electronic optimization circuits, i.e. in hardware, or in hybrid form, i.e. by means of software components and hardware components.
  • the characterizing features according to the invention particularly have the advantage that an efficient system of operating a network is provided in which collisions between signals transmitted at the same time or during the same time interval via the same channel by different devices can be prevented, access to the medium is accelerated and thereby packet delay reduced, and simultaneously the channel capacity is used in an efficient manner.
  • a network node may check whether there is another free channel on which the counting down of the Backoff time may be continued. In case that the network node finds such a presently free nun-busy channel, it may switch to this other channel without stopping the downcount. In other words, when switching, the Backoff timer may be only stopped, not reset to the initial value. Then, the countdown can be continued on this other channel, and after expiry of the remaining part of the Backoff time, the network node sends traffic over the destination channel to which it has switched.
  • a method improving the throughput and delay of prioritized stations in a network that uses Carrier Sense Multiple Access (CSMA) as a Medium Access (MAC) method is provided.
  • CSMA Carrier Sense Multiple Access
  • MAC Medium Access
  • Such a method may be denoted as a "Smart Backoff' method and may apply to networks with multiple data channels. These channels can be code divided, frequency divided, time divided or space divided.
  • a Backoff mechanism may be applied to avoid packet collisions of several transmission stations.
  • the Backoff mechanism according to an exemplary embodiment of the invention allows to carry out a Backoff across multiple channels. If one channel is getting busy during a Backoff countdown, the Backoff can be continued on a different channel.
  • a subsequent transmission can be carried out on a different channel to avoid a so-called post- Backoff.
  • Such a scheme can significantly reduce the packet delay and increase the data throughput in a CSMA system.
  • a system is provided in which stations carry out a decentralized Backoff mechanism to spread out their Backoff times to a minimum. According to an exemplary embodiment of the invention, this can be done very efficiently, since channel bandwidth may be used by jumping to presently unused or non- busy channels, in order to continue with counting down the Backoff time.
  • exemplary embodiments of the invention may provide significant advantages particularly in real time connections and in scenarios with many stations or network nodes.
  • the so-called smart Backoff procedure may be provided. This procedure can be applied to all systems where transmission in different channels is possible.
  • the Backoff procedure according to an exemplary embodiment of the invention thus may solve the shortcomings of the conventional Backoff, which only considers the access with the same channel and does not exploit the degree of freedom that multiple channels offer.
  • embodiments of the invention may increase the flexibility in using the available channel capacities.
  • Exemplary fields of application of systems according to embodiments of the invention are all devices that apply a Backoff mechanism and have the possibility to access different communication channels. Such devices may be provided for the purpose of wireless or wired data transmission.
  • An exemplary standard to which embodiments of the invention apply is IEEE 802.11 , particularly IEEE 802.1 In.
  • the system according to an embodiment of the invention may be implemented in the context of a WLAN (Wireless Local Area Network).
  • a method for contending for access to a communication medium comprising a Backoff procedure in which, in case of a channel detected to become busy during counting down the Backoff time, the corresponding network node may switch to another channel.
  • a communication station arranged for contending for access to a communication medium in accordance with such a Backoff procedure may be provided.
  • a communication system comprising a plurality of communication stations may be provided, wherein the respective communication stations are arranged for contending for access to a communication medium in accordance with a Backoff procedure as described herein.
  • a method of transmit Backoff for a medium access control protocol in a communication network including a plurality of stations in a plurality of code, frequency or time channels may comprise that a first station starts a Backoff on a first channel by selecting the time (slots) to wait before a transmission and starting a countdown of time (slots).
  • the first station may search for another free channel and may continue its down-count of time (slots) on this second channel without freezing the Backoff count during the transmission of said second station.
  • said second station may transmit pending data on said second channel at the completion of the down-count (eventually after an additional fixed pause time) in case of an idle medium on the second channel.
  • Such a method may further comprise that the first station may start a new Backoff after completion of the transmission of the same channel on which the transmission was carried out (so-called post-Backoff). Furthermore, the first station may not have to start a post-Backoff of any other channel than the channel of the previous transition, i.e. in case of data pending, immediately starting an additional transmission on one of said other channels (without performing post-Backoff on this other channel).
  • the channels may be code channels defined according to Multi-Carrier Code Division Multiple Access (MC-CDMA) principles.
  • a communication network including a plurality of stations in a plurality of code, frequency or time channels
  • a particular station may employ a Backoff scheme comprising starting a Backoff on a first channel by selecting the time (slots) to wait before a transmission and starting a down-count of time (slots).
  • the station may search for another free channel and may continue its down-count of time (slots) on the second channel without freezing the Backoff counter during the transmission of the other station.
  • pending data may be transmitted on said second channel at the completion of the down-count (eventually after an additional fixed pause time), i.e.
  • a new Backoff may be started after completion of the transmission on the same channel on which the transmission was carried out (post-Backoff).
  • post-Backoff is started on any other channel than the channel of the previous transmission, i.e. in case of data pending, an additional transmission may be started immediately on one of said other channels (without performing post-Backoff on this other channel).
  • a communication station comprising a transmitter, a receiver, a processor and a local storage.
  • the processor may be configured to run a Backoff scheme comprising the steps as described above referring to the communication network.
  • the method may comprise transmitting the signal via the other one of the communication channels after having counted down the pre-determined waiting time to zero.
  • the communication message may be sent via the channel to which the network node has switched.
  • the method may comprise detecting, during the continuing of the counting down, whether the other one of the communication channels becomes busy, and in case that the other one of the communication channels has become busy during the continuing of the counting down, the network node may switch to a further one of the communication channels and may continue the counting down on the further one of the communication channels.
  • the network node switches its channel a second (or even a third, a fourth, and so on) time in order to provide a sufficient bandwidth even in a scenario in which it happens multiple times that, during Backoff, the presently envisaged channel become busy.
  • a repeated channel switching may thus further improve the performance of the entire system.
  • the method may further comprise transmitting the signal via the further one of the communication channels after having counted down the pre-determined waiting time to zero.
  • the last channel which remains free even after expiry of the Backoff time can be used for data transmission.
  • the method may further comprise, after having transmitted the signal via the other one of the communication channels, preventing the network node from transmitting a further signal via the one of the communication channels for a pre-determined (fixed or randomly selected) further waiting time, and enabling the network node for immediately or after a shortened further pre-determined waiting transmitting a further signal via a further one of the communication channels.
  • a post-Backoff process may be made much more efficient according to an embodiment of the invention. After having sent the message by the communication channel which remains free during expiry of the Backoff time, this network node is prevented from sending data messages on the same channel, for priority reasons.
  • such a communication node which has just sent a communication message may use any other of (presently or potentially free) channels so as to use free capacity and bandwidth in an efficient manner.
  • other channels than the one which has just been used for transmission can be used at once or after a shortened waiting time
  • the method may comprise transmitting the signal via the selected one of the communication channels after having counted down the pre-determined waiting time to zero on the selected one of the communication channels, and after having transmitted the signal via the selected one of the communication channels, the network node may be prevented from transmitting a further signal via the selected one of the communication channels for a pre-determined further waiting time, and the network node may be enabled for immediately or after a shortened further pre-determined waiting time transmitting a further signal via a further other one of the communication channels.
  • the switching to another one of the communication channels may be performed based on scanning the communication channels sequentially or simultaneously.
  • any of the network nodes may scan the available channels according to a predetermined algorithm or scheme, for example one after the other. Such a separate or sequential scanning may also be performed in a random manner.
  • all of the communication channels may be monitored simultaneously, that is to say parallel in time.
  • code-based channels like e.g. in the MC-CDMA embodiment, or, in case of frequency-based channels, with devices that are equipped with multiple transceivers.
  • the signal to be transmitted may be a data packet.
  • the data signal is retransmitted on another, i.e. a changed, transmission channel, after expiry of the Backoff time.
  • the method may implement a Carrier Sense Multiple Access as a Media Access method.
  • Carrier Sense Multiple Access may be denoted as a non-deterministic Media Access Control (MAC) protocol in which a node verifies the absence of other traffic before transmitting on a shared physical medium, such as an electrical bus, or a band of an electromagnetic spectrum.
  • MAC Media Access Control
  • Carrier Sense may denote that a transmitter listens for carrier waves before trying to send.
  • Multiple Access may denote that multiple nodes send and receive on a medium.
  • the network node may be adapted to communicate according to the IEEE
  • the IEEE 802.11 standard (see LAN MAN Standards Committee of the IEEE Computer Society, Wireless LAN Medium Access Control (MAN) and Physical Layer (PHY) specifications, IEEE Standard 802.11, 1999 Edition).
  • the IEEE 802.11 standard is a standard that specifies carrier sense media access control and physical layer specifications. Wireless LANs may operate in the 2.4 GHz band.
  • the network node may be adapted to communicate according to the IEEE 802.1 In standard, being a new sub-standard of the worldwide IEEE 802.11 standard for Wireless Local Area Networks (WLANs).
  • the IEEE 802.1 In standard is a standard that specifies a technique for establishing of wireless local networks with data rates in the range of, for instance, 540 Mbps.
  • IEEE 802. Hn may use Multiple Input Multiple Output (MIMO) for data transmission.
  • MIMO Multiple Input Multiple Output
  • the plurality of communication channels may be at least one of frequency- based communication channels, code-based communication channels, and time-based communication channels.
  • the plurality of communication channels of the network may be distinguished in frequency or with codes. For instance, channels are separated with codes (CDMA, "Code Division Multiple Access”) or in frequency (FDMA, "Frequency Division Multiple Access”).
  • the plurality of communication channels may be adapted for Multi-Carrier Code Division Multiple Access (MC-CDMA) or for Direct- Sequence Code Division Multiple Access (DS-CDMA).
  • MC-CDMA Multi-Carrier Code Division Multiple Access
  • DS-CDMA Direct- Sequence Code Division Multiple Access
  • a multi-carrier system may be particularly denoted as a system where the several sub-carriers are used for parallel transmission of data packets.
  • a multi-carrier mechanism may be applied to a Code Division Multiple Access (CDMA) network.
  • CDMA Code Division Multiple Access
  • each data symbol may be spread over a large bandwidth, preferably larger than the bandwidth needed for transmission. This may allow to transmit with a spectral energy that is lower than in a non-spread spectrum system. This may allow for the use of parallel transmission channels at the same time and in the same frequency band.
  • MAC Medium Access Control
  • the pre-determined waiting time may be a Backoff time.
  • a host or node which has experienced a collision on a network may wait for an amount of time before attempting to retransmit.
  • a random Backoff may reduce the probability that the same nodes will collide again, even if they are using the same Backoff algorithm.
  • Increasing the Backoff period after each collision may also help to prevent repeated collisions, especially when the network is heavily loaded.
  • the method may comprise pre-determining the Backoff time to be a multiple (an integer multiple) of a pre-determined time slot.
  • the duration of the time may be a multiple of a slot time (which may be, for instance, 9 ⁇ s).
  • Each station may maintain a so-called Contention Window (CW), which may be used to determine the number of slot times a station has to wait before starting a transmission.
  • CW Contention Window
  • CW may have a minimum starting value of 15 and it may be increased (for example doubled) after a packet collision. Its value can rise, for instance up to 255, and may be decremented after a successful transfer. The increase of the CW size may reduce the probability that the same packets collide again.
  • the method may further comprise waiting for a pre-determined (fixed or randomly selected) pause time before transmitting the signal via the further one of the communication channels and after having counted down the pre-determined waiting time to zero.
  • a pre-determined fixed or randomly selected
  • collisions on the iurther channel can further be reduced.
  • exemplary embodiments of the network node will be described. However, these embodiments also apply for the method of operating a network node, for the communication network, for the computer-readable medium and for the program element.
  • the network node may be realized as a computer device, particularly as a personal computer, as a laptop computer, as a workstation, as a PDA
  • the network node may also be realized as, for instance, a mobile phone, or the like.
  • the network node may further comprise a transmitter, a receiver and a local memory.
  • the transmitter and the receiver may be coupled to the communication channels.
  • the transmitter may transmit signals to the communication channels.
  • the receiver may receive signals from the communication channels.
  • the local memory may be coupled to the processor and may be adapted to store data.
  • the local memory can be, for instance, an EEPROM.
  • the transmitter and the receiver may also be coupled to the processor, as well as the local memory device.
  • the processor may be a microprocessor or the like.
  • the communication network may comprise a plurality of interconnected network nodes having the above-mentioned features.
  • the network system may be a wireless communication system for allowing a wireless communication between the plurality of network nodes, thus forming a wireless network. Nodes of such a network may communicate with each other, for instance, via a transmission of electromagnetic waves.
  • a network can be a WLAN (Wireless Local Area Network).
  • the network system may be conventionally wired, i.e. the different network nodes may be connected with each other using electrical wires.
  • Fig. 1 shows a network system according to an exemplary embodiment of the invention.
  • Fig. 2 shows a communication device according to an exemplary embodiment of the invention.
  • Fig. 3 shows a communication scheme according to an exemplary embodiment of the invention.
  • Fig. 4 shows a communication scheme according to an exemplary embodiment of the invention.
  • Fig. 5A to Fig. 5C show the time dependence of traffic transmitted via different channels of network systems according to an exemplary embodiment of the invention.
  • Fig. 6 shows the time dependence of traffic transmitted via different channels of a network system according to the prior art.
  • a communication network 100 according to an exemplary embodiment of the invention will be described.
  • Fig. 1 shows the communication network 100 comprising a first computer terminal 101 (a first station), a second computer terminal 102(a second station), a third computer terminal 103 (a third station) and a fourth computer terminal 104 (a forth station), each having a processor (not shown in Fig. 1).
  • the computer terminals 101 to 104 are interconnected in a wireless manner via a first channel 105, a second channel 106 and a third channel 107. Via any of the communication channels 105 to 107, any of the computer terminals 101 to 104 can transmit data to any other one of the computer terminals 101 to 104 in a wireless manner.
  • Each of the computers 101 to 104 is adapted to communicate according to the IEEE 802.11 standard, the network system 100 forming a WLAN.
  • the computer terminal 101 comprises a microprocessor (CPU) 200, comprises at least one transmitter 201 coupled to the microprocessor 200 and wirelessly coupled to any of the communication channels 105 to 107 for transmitting data packets onto any one of these channels 105 to 107, and comprises at least one receiver 202 coupled to the microprocessor 200 and adapted to receive data packets from any one of the channels 105 to 107.
  • CPU microprocessor
  • a rewritable memory 203 is provided and coupled with the microprocessor 200. Data may be stored in the memory 203 under control of the microprocessor 200.
  • the terminal computer 101 serves as a network node in the communication network 100 which comprises the plurality of network nodes 101 to 104 which are communicatively coupled via the plurality of communication channels 105 to 107.
  • the terminal computer 101 comprises the microprocessor 200 which is adapted to carry out the method which will be described in the following.
  • the processor 200 may count down a pre-determined Backoff time before transmitting the data packet via the, for instance, first communication channel 105. While the Backoff time is counted down, the processor 200 may detect whether the first communication channel 105, via which the computer terminal 101 desires to send a communication message, becomes busy. Such an event may occur, for instance, when the second terminal computer 102 starts emitting a signal and transmitting it via the first communication channel 105 during the countdown of the Backoff time by the processor 200 of the first terminal 101.
  • the processor 200 may switch to, for example, the second communication channel 106 and may continue the counting down of the Backoff time on this second communication channel 106.
  • the processor 200 may detect this, may switch to the third communication channel 107, and may continue the counting down on the third communication channel 107. After the expiry of the entire Backoff time, the processor 200 may finally send the data packet via the third transmission channel 107.
  • FIG. 3 another scenario will be described which may happen when operating the network system 100.
  • the first computer terminal 101 wishes to send a data packet via the first communication channel 105 and therefore starts to count down a Backoff time 301.
  • the fourth computer terminal 104 sends a data packet 302 on the first channel 105.
  • This can be detected by the processor 200 of the first computer terminal 101 so that the first computer terminal 101 may switch to the second, presently free, communication channel 106 to continue the counting down of the Backoff timer 301 there.
  • Such a switch is indicated with the reference numeral 303 in Fig. 3.
  • no one of the other network nodes 102 to 104 disturbs the channel 106 which thus remains free. Therefore, after expiry of the Backoff time 301, the first computer terminal 101 sends the data packet 304 via the second communication channel 106.
  • the third computer terminal 103 independently from this, during counting down the remaining part of the Backoff timer 301, the third computer terminal 103 sends a data packet 305 via the third communication channel 107.
  • the first computer terminal 101 would be conventionally necessary for the first computer terminal 101 to perform a further post-Backoff counting down before sending a further communication message. According to the described embodiment of the invention, such a post-Backoff will also be possible in case that the first computer terminal 101 would desire to send a further data packet via the already used second communication channel 106. However, in order to increase the bandwidth, it is possible for the processor 200 to detect that the first communication channel 105 is now free, thus allowing the processor 200 to send a further data packet 306 on the first communication channel 105 immediately after having sent the data packet 304 via the second communication channel 106. The jump from the second communication channel 106 to the first communication channel 105 prior to sending the further data packet 306 on the first communication channel 105 is denoted with reference numeral 307.
  • Fig. 4 four communication channels 105 to 107, 401 are shown which may be denoted as "codechannels”.
  • a first station using a smart Backoff system starts its Backoff in the usual way, see reference numeral 402 indicating counting down a Backoff time. If this Backoff is interrupted by the transmission of a data packet 403 by a second station, the first station searches for another free channel and finds the third channel 107 so that the first station performs a channel jump 404. Then, the first station continues its down-count with the Backoff timer 402.
  • This channel change or switch may be repeated (one or several times) until the Backoff timer 402 reaches zero and the first station is allowed to transmit its message.
  • the smart Backoff gives prioritized stations, that are allowed to use it, a faster transmission possibility, resulting in a higher throughput and lower packet transfer delay.
  • a second jump is indicated in Fig. 4 with reference numeral 405 and may occur when a data packet 406 is transmitted by another station on the third channel 107.
  • This jump 405 goes from the third channel 107 to the second channel 106 at which the countdown of the Backoff timer 402 is finished.
  • the first station sends a communication data packet 407 via the second channel 106 at which the countdown of the Backoff timer 402 has been finished.
  • Another aspect of an embodiment of the invention concerns post-Backoff.
  • a station "A" completed a transmission on a first channel and therefore has to defer from the medium setting a post-Backoff timer. If the station "A" is allowed to use the smart Backoff, it starts a post-Backoff timer on channel 1 (on which it transmitted the last packet), but can transmit in any free channel immediately (without performing the post-Backoff), thus achieving higher Quality of Service (QoS) in terms of throughput and transmission delay.
  • QoS Quality of Service
  • a system may be provided comprising multiple code channels. Such a system could be, for instance, a MC-CDMA or DS-CDMA system.
  • switching the channel may be a fast operation, as a switch may take place in a digital logic of the transceiver, respectively signal processor.
  • a station After being blocked on one channel by a transmission of another station or having completed an own transmission, a station switches its code channel and searches for the idle channel on which to continue its Backoff, respectively start transmission. This scanning of other channels may be carried out sequentially or even in parallel.
  • the system may comprise multiple frequency channels, as shown in Fig. 5A, Fig. 5B, and Fig. 5C.
  • Fig. 5A to 5C shows smart Backoff and multiple channels with DIFS switching time.
  • code channel blocking through alien transmission is denoted with reference numeral 500. Furthermore, data transfer after Backoff 501 is shown, Backoff slot intervals 503, and DIFS 502.
  • channel switching may require a little more time as analog components might be involved. However, even in this scenario switching may be improved to get a better efficiency of channel use.
  • the switching times can be reduced or even avoided completely, particularly if certain components in the transceiver are present multiple times like, e.g. oscillators or complete transmit and receive chains. By such a redundancy, the efficiency can be further improved.

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  • Mobile Radio Communication Systems (AREA)

Abstract

L'invention concerne un procédé pour utiliser un noeud (101) d'un réseau de communication (100) comportant une pluralité de noeuds (101 à 104) communiquant par une pluralité de canaux (105 à 107) de communication. Ce procédé consiste à faire le compte à rebours d'un temps d'attente (301) défini, avant de transmettre un signal (304) par un canal sélectionné (105) parmi les canaux de communication, à déterminer si, pendant le compte à rebours, le canal de communication sélectionné (105) est occupé et, si c'est le cas, à commuter sur un des autres canaux de communication (106) et à poursuivre le compte à rebours sur cet autre canal de communication (106).
PCT/IB2006/050980 2005-04-08 2006-03-31 Procede pour utiliser un noeud d'un reseau de communication, noeud de reseau, reseau de communication, support lisible par ordinateur et element de programme WO2006106459A1 (fr)

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EP05102813.2 2005-04-08
EP05102813 2005-04-08
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EP05109377 2005-10-10

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Cited By (9)

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EP2180750A1 (fr) * 2008-10-23 2010-04-28 Thomson Licensing Sélection de créneaux de transmission pour le procédé de retard déterministique de transmission en commande d'accès au support
US9451627B1 (en) 2014-12-16 2016-09-20 Silvus Technologies, Inc. Single transceiver-DSA via MAC-underlay sensing and signaling
US10820182B1 (en) 2019-06-13 2020-10-27 David E. Newman Wireless protocols for emergency message transmission
US10820349B2 (en) 2018-12-20 2020-10-27 Autonomous Roadway Intelligence, Llc Wireless message collision avoidance with high throughput
US10939471B2 (en) 2019-06-13 2021-03-02 David E. Newman Managed transmission of wireless DAT messages
US11153780B1 (en) 2020-11-13 2021-10-19 Ultralogic 5G, Llc Selecting a modulation table to mitigate 5G message faults
US11202198B1 (en) 2020-12-04 2021-12-14 Ultralogic 5G, Llc Managed database of recipient addresses for fast 5G message delivery
WO2023090711A1 (fr) * 2021-11-17 2023-05-25 삼성전자 주식회사 Dispositif électronique de balayage de liaisons et son procédé de fonctionnement
US11963026B2 (en) 2019-09-03 2024-04-16 Silvus Technologies, Inc. User interface for MIMO networks

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EP1424814A1 (fr) * 2002-11-26 2004-06-02 Texas Instruments Incorporated Réglage adaptatif des temps de backoff pour des communications dans un réseau sans fil
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EP1424814A1 (fr) * 2002-11-26 2004-06-02 Texas Instruments Incorporated Réglage adaptatif des temps de backoff pour des communications dans un réseau sans fil
US20050070317A1 (en) * 2003-09-30 2005-03-31 Intel Corporation Systems and methods for contention control in wireless networks

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2180750A1 (fr) * 2008-10-23 2010-04-28 Thomson Licensing Sélection de créneaux de transmission pour le procédé de retard déterministique de transmission en commande d'accès au support
WO2010047763A1 (fr) * 2008-10-23 2010-04-29 Thomson Licensing Sélection de lots de transmission du procédé de réduction de puissance déterministe au repos dans la commande d’accès au support
US8817640B2 (en) 2008-10-23 2014-08-26 Thomson Licensing Selection of transmission lots of the relaxed deterministic back-off methods in the medium access control
CN102197699B (zh) * 2008-10-23 2015-05-13 汤姆森特许公司 介质访问控制中松弛确定性回退方法的传输时隙选择
US9451627B1 (en) 2014-12-16 2016-09-20 Silvus Technologies, Inc. Single transceiver-DSA via MAC-underlay sensing and signaling
US10820349B2 (en) 2018-12-20 2020-10-27 Autonomous Roadway Intelligence, Llc Wireless message collision avoidance with high throughput
US20220304055A1 (en) * 2018-12-20 2022-09-22 David E. Newman Wireless message collision avoidance with high throughput
US10939471B2 (en) 2019-06-13 2021-03-02 David E. Newman Managed transmission of wireless DAT messages
US11160111B2 (en) 2019-06-13 2021-10-26 Ultralogic 5G, Llc Managed transmission of wireless DAT messages
US10820182B1 (en) 2019-06-13 2020-10-27 David E. Newman Wireless protocols for emergency message transmission
US11963026B2 (en) 2019-09-03 2024-04-16 Silvus Technologies, Inc. User interface for MIMO networks
US11153780B1 (en) 2020-11-13 2021-10-19 Ultralogic 5G, Llc Selecting a modulation table to mitigate 5G message faults
US11206169B1 (en) 2020-11-13 2021-12-21 Ultralogic 5G, Llc Asymmetric modulation for high-reliability 5G communications
US11206092B1 (en) 2020-11-13 2021-12-21 Ultralogic 5G, Llc Artificial intelligence for predicting 5G network performance
US11832128B2 (en) 2020-11-13 2023-11-28 Ultralogic 6G, Llc Fault detection and mitigation based on fault types in 5G/6G
US11202198B1 (en) 2020-12-04 2021-12-14 Ultralogic 5G, Llc Managed database of recipient addresses for fast 5G message delivery
US11395135B2 (en) 2020-12-04 2022-07-19 Ultralogic 6G, Llc Rapid multi-hop message transfer in 5G and 6G
US11438761B2 (en) 2020-12-04 2022-09-06 Ultralogic 6G, Llc Synchronous transmission of scheduling request and BSR message in 5G/6G
US11297643B1 (en) 2020-12-04 2022-04-05 Ultralogic SG, LLC Temporary QoS elevation for high-priority 5G messages
US11229063B1 (en) 2020-12-04 2022-01-18 Ultralogic 5G, Llc Early disclosure of destination address for fast information transfer in 5G
US11212831B1 (en) 2020-12-04 2021-12-28 Ultralogic 5G, Llc Rapid uplink access by modulation of 5G scheduling requests
WO2023090711A1 (fr) * 2021-11-17 2023-05-25 삼성전자 주식회사 Dispositif électronique de balayage de liaisons et son procédé de fonctionnement

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